Method of and apparatus for isolating minerals



"March 1939- HQL. ALEXANDER ET AL 2,151,578

METHOD OF AND APPARATUS FOR. ISOLATING MINERALS Filed Feb. '7, 1959 1sSheets-Sheet 1 mvsu-roas ATTORNEY 4mm. 10 U a u a wa v 448% 4r 9 mam a 2U I Haw Mal'ch 1939- H. L. ALEXANDER ET AL 2,151,578

METHOD OF ANX D APPARATUS FOR ISOLATING MINERALS Filed Feb. 7:, 1939 1sSheets-Sheet 2 HezzzyL/I/exanoer Huber! .1. Du am Willing /3.F5u/KemvsNToRs J06 BY v w ATTORNEY- March 21, 1939 H. LIALEXANDER ET AL2,151,578

- METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Feb. 7, 19:59 1eSheets-Sheet 3 Huberz Z DqPam BY WZ'Z/z'zgg ZiEu/Ke March 1939- H. L.ALEXANDER ET AL METHOD OF AND APPARATUS FOR ISOLATING MINERALS 16Sheets-Sheet 4 Filed Feb. 7, 1959 QM v E W 0 7 4 NA. n E .w

am a v NNN March 21, 1939. H. ALEXANDER ET AL 2,151,578

' METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Feb. 7, 1959 1Sheets-Sheet s 3- dmunuuun 1 A Ewmm Hzmy LAlexazzc/er ,NVENTORS Huber!Du/ 0m BY Wzllmg /3. Foal/K fi ATTORNEY March 21, 1939. H. ALEXANDER ETAL 2,151,578

METHOD OF AND APPARATUS. FOR ISOLATING MINERALS 16 Shets-Sheet 6 FiledFeb. 7, 1939 HeZ7 yL A] I INVENTORS fiuberz ZDz/Pam WWI/17y 15. Fall/XeBY v I I ATTORNEY March 21,1939; H. ALEXANDER 'ET AL 2,151,578

' METHOD OF AND APPARATUS FOR IS6LATINGMINERALS Filed Feb. 7, 1959 16Sheets-Sheet. 9'

ooqocOaOOc-oono an ooo'ngo'coc I INVENTORS Henry LlAIexander Huber! 1'.DuPanz Willing fif'oulke March 1939 H.YL. ALEXANDER ET 'AL METHOD OF ANDAPPARATUS FOR ISOLATING MINERALS Filed Feb. 7, 1959 16 Sheets-Sheet 10 e1.81., aP zv X kDm. 7 9 h r v 07. a U ma.

ATTORNEY March 21, 1939. L ALEXANDER 2,151,578

METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Feb. 7, 1939 16Sheets-Sheet 11 @w YTT INVENTORS ATTORNEY M 3 .wwf

HA HA Hul 1 a MW/v I 5 mm". W

March 21, 1939. ALEXANDER ET AL V r 2,151,578

METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Feb. 7 1959 16sheetsesheet l2 401 7 427? Henry LA/exana'er V T' R,

Huber! [Du/ 0m 4 405 Willzl'zg /3.Foz//Ke 4Z6 v ATTORNEY March 21, 1939.H. 1.. ALEXANDER ET AL I 2,151,573

METHOD OF AND ABPARATUS FOR ISOLATING MINERALS Filed Feb. 7, 1959 1eSheets-Sheet 1s HzmyLA/axanaar Va/barf IDuPom Wz'I/z'zgg /3.FoulkeINVE'NTORS March 21, 1939 H. ALEXANDER ET AL 2,151,578

METHOD OF AND APPARATUS FOR ISOLATING MINERALS Filed Feb. 7, 1939 16Sheets-Sheet 14 I ll I 61 ii'iiiilll M 3 H. L. ALEXANDER ET AL.2,151,578

METHOD OF AND APPARATUS FOR ISOLATING' MINERALS Filed Feb. 7, 19 39 16Sheets-Sheet 16 Henry LA Zexanaer mam-- Huber! ZDuPom WiZ/izgg B. Fay/XeINVENTORS Patented Mar. 21, 1939 UNITED STATES PATENT OFFICE METHOD OFAND'APPARATUS FOR ISOLAT- ING MINERALS Henry L.

Alexander, Niagara Falls, N. Y., and

Application February 7, 1939, Serial No. 255,014

In Germany August 27, 1937 24 Claims.

This invention relates to the separation of minerals from gangue by theuse of a liquid of specific gravity between that of the mineral and thegangue.

3 applied to the separation of coal from its indigenous impurities,particularly slate, a separation in which the process and apparatus areof particularly great value, but it is to be understood that thisdescription is illustrative, not limitative.

l Coal appears to have been known to, and to the United States only thethick seams were.

mined. Hand methods of mining were used and 39 the use of anythingexcept hand cleaning, or the most crude of mechanical methods, wasunnecessary. As the thick seams were used up, however, it becamenecessary to use thin seams and seams containing veins of rock, whichentailed the g5 necessity of removing the rock before the coal could besold. The method which came most prominently into use, and which istoday the standard of separating coal and slate, depends upon the ratesat which bodies of diiferent densi- 30 ties sink through a liquid suchas water. It is known that bodies sink through a liquid at rates whichare functions of their respective densities, the denser sink the moreswiftly. The standard jig washer of the industry takes advantage of 35this principle, but instead of permitting the solids to sink through theliquid, the liquid is forced through a screen on which the solids restat a rate which lifts the layer of coal off the heavier slate, the coalbeing carried with the rush of 40 =liquid over a weir andlthe slatebeing discharged A at a lower point from the screen. Jigs are highlydeveloped and are of excellent capacity and performance. However, thecompetition of oil has driven coal producers to find means of cleaning45 coal which will be more accurate in separating useful from usele$lumps and .producers and inventors have, turned their thoughts to thoseprocesses of separation which depend upon the parting action of a liquidhaving specific gravity 50 between that of coal and that of slate.

The use of a parting liquid is to be distinguished from froth flotation.,Froth flotation alters the apparent specific gravity or finely dividedbodies so that they float on a liquid of less actual dent sity. Partingprocesses, however, dependupon The invention will bedescribed as it isthe use of a parting liquid in which one ingredient of the mixture willsink down and another ingredient of the mixture will rise to and floaton the top. Certain phases of the parting liquid process are affected bythe phenomenon of altered specific 5 gravity, but they are distinguishedfrom froth flotation.

The suggestion was made toward the middle of the nineteenth century thatferric chloride (1856), or sulfuric acid could be used as a partingliquid for the separation of coal and slate, and attempts were made inEngland to run the ferric chloride process in competition with the jigs,but the jigs were even then well developed, and the attempt was afailure. The proposed process was ideal in theory, however, andsubsequent inventors attempted to improve it. A. host of patents hasbeen issued particularly in England and in the United States, dealingwith proposed processes of the parting liquid type, but none has beensuco cessful with the possible exception of one that depends upon theparting effect of a suspension of solids such as sand or clay in water.The processes using parting media of homogeneous character are stillinoperative for the reasons that the loss of parting liquid byattachment to the solids makes the process so expensive that theadvantages of more accurate separation are lost; the processesthemselves, being crude and undeveloped, are incapable of competing withthe highly developed processes already in use in the industry; they areincomplete processes, lacking a number of elements essential to success;and the presence of parting liquidson the coal makes the coal inferiorin certain uses. Prior to our invention these objections were known, butno way of overcoming them had been discovered.

It is an object of this invention to prevent the adhesion of an organicsolid and an organic liquid. Another object and also a principal objectof the invention is toseparate coal from impurities by the use of aparting liquid having a specific gravity intermediate that of the coaland the-impurities and: comprising an organic liquid. Anotherobject ofthe invention is to prevent the ad- 'hesion of coal and othercarbonaceous solids and hydrocarbon liquids. Another object of theinvention is to present to the mining industry a coal preparingapparatus capable of using the new process in economical competitionwith the best prior art-processes. Another obpect of the invention is toapply aqueous protective films to minerals that are not readily wet bywater by means of film stabilizers, to list representative and variousmembers of the class of film stabilizer, to

define the said class, and to disclose a definitive method applicable toall known substances by means of which any substance, regardless of itschemical structure or physical condition, can be known qualitatively andquantitatively in its relative efliciency as a film stabilizer. It isalso an object of the invention to produce minerals for delivery with apreselected gangue content. Another object of the invention is toreadily determine the gangue content and specific gravity of mixedsolids. Other objects of the invention will be in part apparent and inpart more fully hereinai'ter set forth.

The objects of, the invention are accomplished, generally speaking, bywetting the materials to be separated with an aqueous solutioncontaining a film stabilizer, washing the materials withwater,'immersing them, preferably under hermetical seal, in a partingliquid of specific gravity intermediate the specific grayities'oi thematerials to be separated, withdrawing the materials from the saidparting liquid after separation, scrubbing the separated constituents,preferably under hermetical seal, with a liquid and ejecting them fromthe process, iortifying the aqueous solution with film stabilizer andreturning it ior reuse, recovering parting liquid from the scrubbingliquid in a semi-static settling system involving continuous flow anddistillation of the sludge, and reusing the scrubbing fluid.

. The broader objects of the invention are accomplished,-generallyspeaking, by immunizing minerals (or other solids, or liquids) which arenot readily wet by water, or which are more readily wet by organicliquids insoluble in water than by water, against contamination by suchorganic liquids by applying thereto an aqueous solution of a filmstabilizer, preferably in dilute solution, before they are brought intocontact with the organic liquid. The film stabilizers are surface activesubstances which in aqueous solution produce an optimum differentialchange in surface tension with respect to concentration atconcentrations of no more than 2% and which form stable aqueous surfacefilmsin the presence of organic liquids essentially insoluble in water.

The objects of the invention are also accomplished in part by theassociation of apparatus, and by the details of the process andapparatus which are more completely elsewhere herein described.

In order to make the drawing more easily comprehensible, the firstfigure has been called the key figure; the steps of the process havebeen numbered from 1 to 9 consecutively and the figures of the drawingshave been numbered to correspond with the steps of the process to whichthey refer. For example, on the key figure the numeral 3 refers to thethird step of the process which involves the actual parting step. Thesheets which relate to that step are numbered from Figure 3 to FigureBl. Furthermore, the parts of apparatus belonging to a certain step inthe process are given a number the first of which'corresponds to thenumber of the step in the process. .Thus, the elements of the apparatusshown in Figures 1 to 11 inclusive begin with thenumber 1.

In the drawings Figure 1- is 'a cross-sectional A view of an apparatuscapable of satisfactorily performing the step of, coating the coal witha solution of water and a film stabilizer; Figure 1a. is a cross-sectionon the line la, la of Figure 1; Figure 1b is a plan view of the hopperand conarc ers veyor tank shown in Figure 1; Figure ic is across-section on the line He, E0 of Figure 1; Figure id is a plan viewof the conveyor pan taken on the line id, id oi Figure 1; and Figure 1cis a perspective view partly in section showing details of theconveyorpan and flights; Figure 1f is a detail; and Figure lg is a detail.Figure 2 is a cross-section through an appa ratus capable of performingthe second step in the process. Figure 2a is a plan view on the line 2a,2a of Figure 2; Figure 2b is a plan iew of the shaker screen shown inFigure 2; Figure 2c is a cross-section on the line 20, 2c, of Figure 2;Figure 211 is a plan View of the settling cone which serves for therecovery .of film stabilizer Wfihfid from the coal by the apparatus ofFigures 2 to 20; Figure 2c is an elevation partly in section of the saidsettling cone.

Figure 3 is an apparatus capable of carrying out the third, parting,step of the process; Figure 3 is a vertical section on the line A-A ofthe key figure; Figure 3a is a cross-section on the broken line 3a, 3aof Figure 3;- Figure 3b is a detail, partly in section, of a preferredmodification of wedge hilt-3M; Figure 3c is a section on Figure 3?);Figure 3d is an elevational view partly in phantom and partly in sectionshowing the parting apparatus; Figure 3c is a section of line 3e, 3c ofFigure 3d; figure 3) is a section of line 3;, 31 of Figure 3d; Figure 39is a section on line 39', 3g of Figure 3; Figure 3h is a section on line3h, 3m of Figure 3; Figure 31' is a section on line 3i, 3: of Figure 3;Figure 37' shows means for operating the preferred embodiment of Figures3b and 30; Figures 3k and 32 show a preferred method of operating theapparatus of Figures 3b and 30.

Figure 4 is an elevational view partly broken away and in sectionshowing the scrubbing aption of Figure 4b taken on the line ZZ of Figure4d; the middle section of Figure 412 being taken on the line Y-Y ofFigure 4d; and the right hand section of Figure ib being taken on theline X-X of Figure 411; Figure 4c is a section on the line do, do ofFigure 4; Figure id is an enlarged section of the sealing mechanismshown in Figure 46; Figure 4c is an enlarged section of a spray pipewith nozzles showing the overlap of the sprays.

Figure 5 discloses the apparatus for receiving material discharged fromthe scrubbing process, for sealing the scrubbing process, and fordischarging the material.

, Figures 6, 6a, 6b, and. 6c disclose the second, or main, settlingtank, being the second step in the heavy liquid recovery system of whichthe first step is the settling tank, the apparatus which is found Withinthe scrubbing section. Figure 6 is a plan view partly cut away and insection of the main settling tank; Figure 6a is a section on the line6a, 6a; Figure'fib is a vertical section on the line 6b, 617; Figure 6cis an enlarged section cross-section of the sludge trap on line lb, 1b;

Figure 7c is a plan view'of the still on the line 10,

1c of Figure 7.

Figures 8 to So do not refer to section 8 of the '-the efficiency .ofseparation can be'expeditiously apparatus, but to an apparatus by meansof which determined. Figure 8 is a plan view of a portion of theapparatus partly in section and Figure 8a is a cross-section on the line8*, 8 i Figure 8. Figure 8b is a drawing of a scoop; Figure 8c is anenlarged detail of the hinge connection. Figure 9 and Figure 9a areviews in plan and elevation, respectively, of the condensers.

Figure 10 is a view of the pipe joints which are used throughout theapparatus.

In order that the invention may be understood in general before beingdescribed in particular, it will first be described with reference tothe key figure.

I indicates a feed conveyor box; Ill indicates a feed hopper attachedthereto; I24 is a means for maintaining the liquid level in the tank'and hopper at a point above the opening between the hopper and the box;II is a chute for supplying broken coal mixed with indigenous impuritiesto the feed hopper Ill; H3 is a conveyor within the hopper which gathersthe 'we'tted material and' ejects it from chute H0. In this first stepof the process the coal is treated with a liquid comprising water and afilm stabilizer. The liquid utilized in this section of the apparatusand in any similar pretreating step is a dilute aqueous solution of afihn stabilizer, the concentration of which is maintained substantiallyconstant.

The mixed coal and slate, having been ejected from chute III], arecaught on screen 2I and are subjected to the second step of the process,which comprises washing the treated coal with water In order to simplifythe comprehension of the invention the path of the coal through theapparatus will be traced to completion before the treatment of usedliquids is-considered.

. From the shaker screen 2| and the second step of the process 2 thecoal is dropped'into chute 328 and is carried thereby into theseparating chamber where the heavy material is separated from thelightby a liquid medium of intermediate specific gravity. After theseparation the coal is drained of entrained liquid and transferred tothe apparatus and step 4 of the process which is, with respect to thecoal, a scrubbing process which removes from the coal substantially allvestiges of parting liquid. In this scrubbing step the separated coaland slate are subjected to a vigorous scrubbing by water, underpressure, which comes from headers 342. The third and fourth steps ofthe process are preferably carried out in a hermeti-.

cally sealed system. The washed coal and slate are ejected through splitboot 462 into the watersealed conveyors 5 which serve to give the coal alast rinsing and to prevent the escape of vapors from the sealed units 3and 4. From the conveyors 5 the coal may be discharged to storage or toa railroad car for transportation to the place of use, and the slate maybe discarded.

Having described the process inv general as it acts upon the coal, theprocess will be described in its relation to the liquids used: When-thecoal has been washed in section 2 of the process'with water from pipes 2I6, the water together with the liquid which it washes off the coalpasses through the screen 2| and is caught-in'the hopper 220 from whenceit is carried by pipe 22I to these-called slit cone 22-2. The sludge isentrapped 'in the chamber 226 and eventually removed through pipe 231.The comparatively clear liquid from the washing step, 1, of the process,diluted with the liquid from sprays 2 I 6, flows over a weir at the toptreating of incoming coal.

of the cone, has its concentration of film stabilizer adjusted byadditions from the tank 240, which contains film stabilizer in moreconcentrated solution, or undissolved, and the line 24l to a percentagethat gives satisfactory results as a pretreating solution, and passesthrough the pipe 243 to the hopper l0 where it is used again for theWhen the coal passes through the scrubbing section 4, it is vigorouslyscrubbed with water from the headers 442. The coal passes on and thewater passes through the screen which carried the coal, and togetherwith sludge and heavy liquid, gathers in tank 406 which forms the lowerpart of this section of the apparatus. From that tank the sludge isremoved through pipe 451 to be discharged into the sludge trap 1, andthe liquid containing lighter suspended matter is discharged into themain settling tank 6. Over the weir at the top of the main settling tank6 flows comparatively clear liquid to be pumped through pipe 6l5 toheaders 442 for reuse in the washing section. From the bottom of thetank 6 the sludge is drawn off through pipe 620 and pumped to the sludgetrap I. From the sludge trap 1 on some occasions substantially theentire contents are dropped into the still 8 for steam distillation, but

in normal and preferred operation the matter isallowed to settle intothree layers, the bottom of I which is largely solid, the middle ofwhich is pumped through pipe 123 to the used liquid stor-- age tank.Finally, the remaining sludge is dropped into the still 8 for steamdistillation. The water, together with vaporized heavy liquid, passesthrough pipe 88-89 to condenser 9 which is diagrammatically shown onthis figure, and from condenser 9 ,to cooler and water separator 96,wherein the heavy liquid is separated by a gravity separation fromwater. The separated heavy liquid is carried through pipes 96I and 962to the new liquid storage tank 963 or the used liquid storage tank 964,respectively. 965 is a vent pipe connecting the used liquid storage tankwith the new liquid storage tank and 966 is a vent from the new liquidstorage tank. The used liquid storage tank can be replenished from thenew liquid storage tank through meter gauge 967, which gives a check onthe amount of liquid used in the system. The level of heavy liquid inthe parting section 3 is maintained by injecting liquid from the usedstorage tank 964 through pipe 359. Excess of heavy liquid escapes over aweir through pipe 358 and back to the used liquid storage tank. In thedrawings a circle with the letter 9 indicates a pump and a circle withthe letter :2: indicates a valve; pipes 358-359 are joined by a pipe inwhich is valve V20.

There were many reasons for the failure of the prior art processes whichattempted to use a parting liquid, but the single reason which renderedthe processes incapable of use and which was insuperable, was the lackof an agent which would maintain a water film on the coal, or

It would sequently,

or more complete film of water and reduce the liquid losses. Such,however, was not the case. For instance, the use of the common wettingagents, sodium petroleum sulfonate, stenolacid phthalate, dilaurylammonium adipate, and sodium-lauryl-sulfate and others produced noimprovement and in many cases actually increased the loss of heavyliquid. Those experiments, and others, showed that the problem involvedwas not one of mere wetting. In carrying out our experiments to developmeans of preventing the adhesion of the parting liquid to the coal, orto other minerals not quickly and preferentially wet by water, wediscovered that the loss of parting liquid could be reduced by applyingan aqueous solution of a film stabilizer to the coal before entering thecoal in the parting liquid. The members of the class of film stabilizerscome from many chemical groups having diverse properties; neverthelesscertain chemical groups fall as a whole within the class. Certainmembers of other groups belong even though the class as a whole is notincluded, an example of which is that some compounds known to haveutility as wetting agents are included because they also possess theproperties of film stabilizers.

Exemplary of the film stabilizers are the following: It is to beunderstood that this list is exemplary; that it 15 not limitative; andthat it is designed to' disclose illustrative examples rather than to bea catalogue of members. Any person interested in cataloging all filmstabilizers from the millions of compounds known, can do so by followingthe definitive process which will be given after the list: catechol,resorcinol, quinol, pyrogallol, dihyclroxy diphenyl, dihydroxychlorbenzene, gallic acid, alizarin, arbutin, ruberythric acid, aloin,aesculin, apiin, glycyrrhizin, pelargonin, tannic acid, digitalin,saponin, parillin, naphthol sulfonic acid, naphthol disulfonic acid,

'naphthylamine disulfonic acid, amino naphthol sulfonic acid, dihydroxynaphthalene disulfonic acid, compound #8, being a condensation productof naphthalene sulfonlc acid and formaldehyde, ID-l, being a reactionproduct of phenol sulfonic acid and formaldehyde, fastan, tanak,irgatan, sulfite cellulose, methyl cellulose, starch acetate, starch,pectin, gum arabic, gum mesquite, gum cherry, gum shiraz, gumghatti,'locust bean gum, gum'karaya, gum tragacanth, carrageen, dextrin,inulin, egg albumin, blood albumin, vegetable albumin, fibrin, edestin,glycinin, alkali soluble protein (sample from corn particularly good),gliadin, casein, gelatin, bone glue, hide glue, rabbit glue,haemoglobin, polyvinyl alcohol, hexamethylene tetramine,triethanolamine, sodium phosphate, oxalic acid, potassium permanganate.

The film stabilizers are surface active substances which in aqueoussolution produce an optimumdiflerential change in surface tension withrespect to concentration at concentrations of no more than about 2% andwhich form stable aqueous surface films in the presence of organicliquids essentially insoluble in water Their function is physical ratherthan chemical and their definition is expressed of necessity in physi,cal or physical-chemical terms. The degree of their solubility in theparting Iii is important because too great solubility in t. partingliquid results in the leaching of the stabilizer out of the water filmand its consequent breakdown. Consolubilities' of surface activesubstances greater than about .3% to about .5%

arenas-a these surface active substances is their of decreasing surfacetension. The lowe surface tension per se is probably not tin. of filmstabilization, but the magnitude a lowering, together with theconcentration a dissolved substance causing the lowerin are dioations cfthe existence at the surioce oi the film of the conditions which causehim stabilization. A given solution forms the most stable films when thegreatest difference exists between the concentration of the filmstabilizer in he surface layer and its concentration in the solution asa whole. The film stabilizing tenden y may be expressed by the ratio ofthe change in surface tension to the concentration at which a surfacetension change is most abrupt. For example, the addition to pure waterof .001% of polyvinyl alcohol produces a surface tension change of 3.60dynes as measured on the du Nouy tensiometer, a ratio of 3.60 to .001 or3600 to l. A similar change of glycerol concentration in water at 10%changes the surface tention by only .5 dyne. The ratio in that instanceis that of .5 to 10 or .05 to 1. On this basis polyvinyl alcohol at.001% concentration is 72,000 times as'good a film stabilizer asglycerol. The film stabilizers produce a relatively great ratioof'change in surface tension for increments of addition atconcentrations less than about 2%, and some of the best produceexcellent results at concentrations as low as .05%. The entrapment ofair on the surface of the mineral as it plunges into the prewetting bathdoes not impair the action of the stabilized film. The stabilized filmsare stable at air-liquid interface and also at liquid-liquid interface,in both cases it being understood that the general conditions ashereindescribed apply. Taking a 5% solution as a standard, thosesurfaceactive substances are useful film stabilizers which show by the additionof that concentration to pure water a surface tension decrease of about.5 dyne or more.

Certain compounds are not themselves film stabilizers but react withmaterials in the system to produce compounds which are film stabilizers.To this class belong sodium phosphate, oxalic acid and potassiumpermanganate. It is within the scope of our invention to add thestabilizers originally orto produce them in the system.

A number of organic materials dissolve in Water to give colloidal ratherthan true solution. The individual micelles are stabilized in thecolloidal state because of their highly hydrated condition, and arethereafter classed as emulsoid" or hydrophile colloids, as distinguishedfrom the suspensoid or hydrophobe colloids which are stabilized by thepresence of an electrical charge. The emulsoid colloids, examplesof'which are found in the above list, are useful as film stabilizers.Among thesubclasses of emulsoid colloids are proteinsand carbohydrates.Among the subclasses of proteins are the albumins, the globulins, theprolamins, the phospho-proteins, the sclero-proteins, and thechrome-proteins. Among the carbohydrates are cellulose derivatives,starches, pectin, gums, seaweed extracts. Emulsoid colloid solutions arecharacterized by relatively high viscosity; a property which can be usedto make-a rough demarcation between that class and other classes bystating that substances which have roughly five or more times theviscosity-increasing eifect of sugar are included, but the true test offilm stabilizing efiiciency with these compounds is apparently theemulsoid col-

